1. Field of the Inventions
The field of the invention relates generally to wireless data communication and more particularly to registering a client device in a wireless data communication system that dynamically assigns network addresses.
2. Background Information
Modern communications systems can be classified into two categories, circuit switched and packet switched. In a circuit switched network, a central switching computer typically establishes connections when communications are established between two devices. Circuit switched network are best suited for delivering information that is continuous, such as voice, music or video. In a packet switched network, packets of data are potentially routed through a plurality of routing devices. Packet switched networks are best suited for delivering information that is burst-like, such as email, web pages, and telemetry. In contrast to the central switching computer each routing device need only know to which device it needs to send the packet to next. As a result, all devices on a circuit switched network have a fixed, essentially permanent (henceforth static) address. An example of such a network is a phone system where the addresses are phone numbers. Devices on a packet switched network may have static address, but with the over abundance of devices on packet switched networks such as the Internet, many service providers ration out address to active devices. These address are often dynamic and can change each time a device becomes active. A typical packet switched network can employ the Internet Protocol (IP) often in conjunction with the transmission control protocol (TCP), jointly referred to as TCP/IP.
A common method of assigning IP addresses to devices is through the Dynamic Host Configuration Protocol (DHCP). A device sends a request to its service provider who issues it an IP address in response. In many applications, devices on a network have a client-server relationship. Many client devices are linked to a server, or a few servers. A server cannot initiate contact with a client device without the client device's IP address. Complicating the ability of a server to track a client device is the fact that the client device's IP address is often valid for only a fixed period of time referred to as a DHCP lease. In some implementations, upon expiration, this lease can be renewed, however, the renewal can result in a different IP address being assigned to the same client device.
An example application of a client-server system is that of a telemetry system. In a telemetry system, client devices are often scattered across several communication service providers and are configured to gather predetermined information such as power usage. On a network with static IP addresses, a central authority can query each device when required. In a network with dynamic IP addresses, however, it cannot initiate contact without the client device's IP address, which may have changed since the last time a particular client device was queried.
In certain implementations, the client devices can use wireless communication links to communicate with the server. In 3rd Generation (3G) wireless communications systems, for example, IP data communications are supported; however, due to the shortage of IP addresses, client devices on these networks are often issued addresses dynamically, e.g. using DHCP. As mentioned above, this can complication communications in certain systems, such as telemetry systems, because the server or servers cannot keep track of the dynamically assigned IP addresses of the client devices. Client devices configured to communicate over 3G communication system often include the capability of receiving data messages over a circuit switched mobile phone network, such as short message services (SMS) messages. Unfortunately, however, constant communications over a circuit switched network for short bursts of data, such as in a telemetry system, is not very efficient and can put a strain on the infrastructure. Therefore, certain systems, such as telemetry systems, may not be able to fully realize the advantage of 3G wireless communication systems.
In many applications, particularly those using wireless networks, security is an additional concern. The nature of IP communications can, in some cases, reduce the transmission security. A properly secure network should at a minimum preserve the integrity of the communications. In addition, a secure network can also protect the privacy of the messages from eavesdropping.